The present invention is an improvement of the apparatus shown in U.S. Pat. No. 3,960,094 granted June 1, 1976 to J. C. Hsiao.
The mechanism shown in the above-identified patent includes a button positioning apparatus mounted on a pivotal clamp. The button positioning apparatus includes a conveyor or turret means rotatably secured to the clamp by a bolt. The conveyor is adapted to receive and automatically index a plurality of buttons or other plate-like articles through a series of steps. In its path to the sewing station, each button is properly aligned by a mechanical orientating mechanism that works in consort with the indexing drive. In operation, the clamp is lowered and the button conveyor means is urged into contact with the workpiece being sewn. Upon completion of the button sewing cycle, the clamp is raised, the sewn button extracted and another orientated button is automatically indexed into the sewing position. Thereafter, the clamp is again lowered and the next button sewing cycle commences.
When the clamp is lowered, a proper relationship between the button conveyor and the machine's work support must be maintained. This relationship is especially apparent in the immediate sewing area. If the button conveyor in not properly maintained with respect to the work support surface, inadequate clamping of the workpiece may result whereby effecting workpiece movement. If the workpiece does not move in consort with the button movement an improper stitch formation can result. Thus, maintenance of a proper clamping relationship between the button conveyor and workpiece support is important.
The relationship between the button turret and work support is easily accomplished when predetermined button thicknesses are being consistently sewn. At the present state of art, however, it is customary to sew one size, shape and design of button one day and a different design, size and shape the next day. This introduction of new or different button sizes presents certain problems. For example, significant or radical changes in button sizes demand various sized button turrets. Understandably, one size button turret cannot functionally accommodate all button sizes. Therefore, various sized button turrets dimensioned as a function of button diameter and thickness are provided. It is easily perceived, however, that the button turret for handling the smallest, thinnest button will be sized differently from that equipped to handle the largest, thickest button. To change button turrets on the apparatus shown in the Hsiao patent affects other machine elements. Without the instant invention, a radical dimensional change in button thickness would require not only a change in button turrets but also a different, correspondingly sized, bolt for securing the turret to the clamp; possibly a new clamp whereby assuring the proper clamping relationship between the turret means and the work support; and a new orientating mechanism with appropriately sized orientating pins. The inventory costs for such a multitude of parts to fit a complete range of button sizes would, of course, be prohibitive. Thus, a compromise in the design of parts, so as to enable operation of the machine on the various button sizes, would appear to be the only feasible alternative to solving the problem.
Significant changes in button thicknesses have other affects as well. A compromise in parts to fit a wide range of button thickness affects the amount of control maintained over the button's planar orientation. Unless the planar orientation of the button is controlled, the buttons could "ride up" on each other whereby causing starvation of the gravity fed buttons to the turret or a jam in the turret, resulting in a machine malfunction. Accordingly, changes in button thicknesses required various dimensioned mechanisms to satisfactorily accommodate various sized buttons.
The mechanisms shown in U.S. Pat. No. 4,069,777 granted on Jan. 24, 1978 to Y. Ishikawa advanced the method of presenting articles to the button turret, but the demand for control of button thicknesses by a modular mechanism remained unanswered. Thus, the heretofore known methods of presenting and indexing a button to a securing station, have serious drawbacks which have heretofore remained unsolved.